<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
  <style>
    
    /* 圆形条纹背景  射击靶 */
    .demo {
      margin: 0 auto;
      width: 205px;
      height: 205px;
      border-radius: 102.5px;
      background: #655;
      background-image: radial-gradient(tan 15px, 
      green 15px 45px,
      red 45px 75px,
      orange 75px 105px);
    }


    /* 波点背景 */
    .demo2 {
      margin: 0 auto;
      width: 600px;
      height: 600px;
      background: #665;
      background-image: radial-gradient(tan 30%, transparent 0), 
                        radial-gradient(tan 30%, transparent 0);
      background-size: 30px 30px;
      background-position: 0 0, 15px 15px;
    }
  </style>
</head>
<body>
  <!-- 圆形条纹背景 射击靶 -->
  <div class="demo">
  </div>
  <!-- 波点背景 -->
  <div class="demo2">
  </div>

</body>
</html>